The present invention relates to the field of medical devices, and particularly to the design and manufacture of external fixation systems. External fixators are used during healing of tissue and particularly during healing of a fractured bone when it is desired to support two bone portions in a fixed position relative to one another during surgery or during healing.
The prior art contains many different types of external bone fixator devices which are used for setting various bone fractures. Many external bone fixator devices employ transcutaneous pins (e.g., K-wires), stakes, screws or other types of bone fasteners, which are secured in the bone or bone fragments on opposing sides of the fracture site. The pins are then secured to an external splint device. The external splint device may use various articulations to adjust its position relative to the bone fasteners. During the fixation surgery, the bone pieces at the fracture may be realigned by the surgeon. The various articulations in the external splint device may assist the surgeon in realigning the bone pieces. Once the external splint device is secured to the bones and the bone pieces are in the desired alignment positions, the articulations in the fixator are locked in place to maintain the bone alignment for a healing duration. Examples of external fixators include the devices and methods taught in U.S. Pat. Nos. 6,056,748, 6,283,964, 6,652,524, 6,746,448 and pending application Ser. No. 10/699,313, all incorporated by reference.
There is a need for improvement in external fixator devices. Many current external fixation systems have a frame which becomes unstable if it is expanded or lengthened. Conversely, if stability of such prior art designs is maximized, the frame is often too short or otherwise unacceptable for correction of the problem. Multiple parts are necessary to allow many prior art frames to be fully functional, the various parts may not be available or may not work well together. Many current external fixation systems include rings, wires, rods and pins which overly obscure the fracture site and create access problems.
Fixator devices need to be strong, rigid and durable, to withstand any forces or inadvertent blows to which the fracture site is subjected. Fixator devices should be lightweight, so as to movable by the patient without extreme difficulty. Fixator devices should be reasonable in manufacturing cost and difficulty. Fixator devices should facilitate a wide range of surgical techniques, to permit the surgeon to best adapt to the particular fracture and to provide the best mode of healing.